Add CLI autoupdate function for n98-magerun2

[Gabriel712]

This PR adds a new autoupdate feature to the n98-magerun2 download script. Users can now run the command "autoupdate" to download and update the n98-magerun2.phar file. The updated file is moved to the bin folder and the user is informed that the update was successful.

Description (*)

Related Pull Requests

Fixed Issues (if relevant)

1. magento/magento2#<issue_number>: Issue title

Manual testing scenarios (*)

1. ...
2. ...

Questions or comments

Contribution checklist (*)

• [x] Pull request has a meaningful description of its purpose
• [ ] All commits are accompanied by meaningful commit messages
• [ ] All new or changed code is covered with unit/integration tests (if applicable)
• [ ] All automated tests passed successfully (all builds are green)